Background: In individuals with a unilateral cleft lip and palate, there routinely exists an abnormality of the facial skeleton in all three planes (transverse, sagittal and coronal). Skeletal and facial asymmetry is pronounced in the anterior part of the maxilla with a smaller maxillary width and height on the cleft side. As a mechanical stimulant, occlusal forces and the resulting stress and strain distribution within the skeletal components lead to strain-induced bone remodeling. This study was done to observe the stress distribution pattern and displacement within the maxillary complex in a complete unilateral cleft lip and palate individual when subjected to simulated occlusal forces, using a three-dimensional finite element analysis.

Material and methods: A three-dimensional finite element model of the maxillary complex of a unilateral cleft lip and palate individual was developed from sequential computed tomography scan images processed at 1-mm intervals. ANSYS™ 14.0 and MIMICS™ software were used for the same. Masseter forces of 300 N were applied at the zygomatic arch bilaterally, and occlusal loads of 100 N were applied vertically onto the framework surface at different locations to simulate occlusal loading. The displacement and von Mises stresses in different planes were studied on different nodes at various anatomical points within the maxillary complex.

Results: The unilateral cleft lip and palate led to a non-uniform, asymmetric stress distribution pattern within the maxillary complex: intensified on the non-cleft side and weakened on the cleft side. An asymmetric displacement pattern was noted between the cleft and non-cleft sides.

Conclusions: The results implied that an individual born with a complete unilateral cleft lip and palate would be expected to have an asymmetric facial development between the non-cleft and cleft sides as a result of an asymmetric occlusal loading pattern.

Keywords: Finite element analysis; Maxillary complex; Simulated occlusal loading; Stress and displacement; Unilateral cleft lip and palate.

© The Author(s) 2025.

背景： 在单侧唇裂和腭裂的个体中，面部骨骼通常会在三个平面上（横向、矢状面和冠状面）存在异常。上颌前部的骨骼和面部不对称尤其明显，表现为患侧上颌宽度和高度较小。作为机械刺激因素，咬合力及其导致的应力和应变分布会促使骨组织发生应变诱导重塑。本研究使用三维有限元分析方法观察在模拟咬合力作用下单侧完全唇裂和腭裂个体中上颌复合体内的应力分布模式及位移情况。

材料与方法： 从连续的计算机断层扫描图像（以1毫米间隔处理）构建了一个单侧唇裂和腭裂患者的上颌复合体三维有限元模型。使用ANSYS™ 14.0 和 MIMICS™ 软件进行建模。在颧弓两侧施加300N咬肌力，并且垂直于不同位置的框架表面施加100N的咬合力，以模拟咬合负荷。研究了上颌复合体中不同解剖点各平面内的位移和von Mises应力分布情况。

结果： 单侧唇裂和腭裂导致了上颌复合体内不均匀、不对称的应力分布模式：非患侧应力增强，而患侧则减弱。在患侧与非患侧之间观察到了不对称位移模式。

结论： 结果表明，单侧完全唇裂和腭裂的个体由于咬合负荷的不对称分布模式，可能会导致非患侧与患侧之间的面部发育不对称。

关键词： 三维有限元分析；上颌复合体；模拟咬合力加载；应力和位移；单侧唇裂和腭裂